1. Field of the Invention
The present invention relates to remote transceivers for two-way cable communications systems and, more particularly, to local remote control means for such remote transceivers.
2. Technical Considerations and Prior Art
In two-way cable communications systems, for example, the systems disclosed in U.S. Pat. Nos. 3,794,922 and 3,803,491, a plurality of remote transceiver units are interrogated and controlled by signals generated downstream from a central or master station. The transmitted interrogation and control signals are generated in the radio-frequency range and are encoded into serially divided successive frame periods including, among other things, a remote transceiver identification code interval, a remote transceiver control code, a remote transceiver function selector code interval and a data readout control interval.
Each remote transceiver includes a number of data encoders and control mechanisms and a transmitter section for transmitting reply data upstream to the master station. The downstream interrogation and control signals are decoded at the remote transceivers and the particular remote transceiver identified is enabled to transmit data signals during the data readout interval. The particular data transmitted upstream is requested by a word count signal transmitted downstream by the master station during the function selector code interval. The upstream data may include, among other things, fire and burglar alarm information and meter readings from water, gas and electric meters or the like.
When utilized in conjunction with a community antenna or cable television system each remote transceiver is associated with a commercial television receiver and includes a converter circuit for converting downstream programs into commercial television frequencies to enable any one of various transmitted programs to be viewed. In this connecting the upstream transmitted data may include program rating data including pay television authorization data and viewer response or opinion data.
When utilized in connection with cable television systems, the remote transceivers may be incorporated into the commercial television receivers associated therewith, but are more often self-contained units or control boxes which are placed on or adjacent to the commercial television receiver. The converter in the control box is tuned by a channel selector, usually a dial, connected to a plurality of camming elements through a common control shaft. Each camming element controls a switch to provide a binary bit to encode the position of the channel selector. The coded channel selector information provides a voltage to a varactor in the converter through a digital-to-analog converter to tune the remote transceiver converter to a desired one of a plurality of channels.
One popular form of remote transceiver includes a remote tuner control which is connected to the control box through a multiconductor cable. With this latter arrangement a problem arises when it is desired to provide program rating information to the central station in order that information as to the channel being viewed be available for transmission to the master station on command. Because of the inconsistencies between varactors, a mere determination of the varactor voltage and subsequent conversion thereof to a digital readout capable of upstream transmission in response to a command from the master station for program rating information is inaccurate.
One technique for providing both remote control tuning and program rating information may include providing a second set of program rating switches in the remote channel selector and a separate group of conductors or a separate cable from the remote channel selector to the remote transceiver. The second set of program rating switches would thus be available to enter the encoded selected channel information into the data readout circuit for transmission upstream to the master station. This solution, however, requires both the size of the remote channel selector and the size of the connecting cable to be increased. Since the remote channel selector units are preferably small enough to be hand-held, this solution renders them unduly cumbersome as well as costly and is thus undesirable.
As taught in the aforementioned patents it is desirable to include viewer response circuitry in the remote transceiver in order to permit the viewer to transmit back to the master station opinions or responses asked of the viewing audience during a particular program. These opinions are usually stated in binary form as "yes" or "no" or "no opinion." It is desirable to provide a range of opinions or other viewer-initiated data in such viewer response circuitry. It would be particularly desirable to provide for a wide range of viewer responses which could be carried out by the viewer from a hand-held remote control such as the remote channel selector without increasing its size or the number of cable conductors connecting it to the remote transceiver control box.